Lucasfilm made the unexpected announcement Thursday. Kasdan co-wrote "The Empire Strikes Back" and "Return of the Jedi," making him a revered figured in "Star Wars" lore. The 64-year-old scribe, who also wrote "Raiders of the Lost Ark," had been serving as a consultant on the film.

"There are few people who fundamentally understand the way a 'Star Wars' story works like Larry," Lucasfilm President Kathleen Kennedy said in a statement. "Michael Arndt has done a terrific job bringing us to this point."

Arndt was named the sole screenwriter last year. He won an Oscar for the script to "Little Miss Sunshine," and also wrote "Toy Story 3" and "The Hunger Games: Catching Fire."

Shooting for "Star Wars: Episode VII" is to start in the spring, with the film due out in 2015.